No. 590] FECUNDITY IN THE DOMESTIC FOWL 



91 



sperm and ova out of the vast hordes the parents produce 

 take part in the production of the resulting litter. He 

 operates, of course, upon the basis that those germ cells 

 which do take part in the formation of the litter constitute 

 a random sample of the whole population. When I put 

 pullets into the house to test their egg production I oper- 

 ate on precisely the same basis, viz., that I have a random 

 sample of the family from which they are taken. As a 

 matter of fact, I have been at great pains to ensure that 

 the sampling should be random. In all of my studies on 

 the inheritance of fecundity I have regarded this as a 

 point of paramount importance, and have never made 

 use (except occasionally for confirmation of points already 

 made out on other material) of families in which I had 

 not either tested all the daughters as to egg production 

 or a sufficiently large random sample to be fairly represen- 

 tative of the family. Further I have repeatedly made 

 careful ad hoc investigations of the adequacy and random- 

 ness of my sampling. 



Castle 's next point is, as the matter stands, apparently 

 well taken. He quotes (p. 715) a statement which I some- 

 what rashly made to the effect "that phsenotypic varia- 

 tion of the character fecundity in fowls, markedly tran- 

 scends, in extent and degree, genotypic variation." Pro- 

 fessor Castle's treatment of this statement is perfectly 

 legitimate. If it were true, as stated, it would admit of 

 being turned around as it is in Castle's next sentence, and 

 then it surely would be silly to talk about either selection 

 for this character or about its Mendelian inheritance. 

 What I should have said when I wrote that unfortunate 

 sentence, but did not, was that phamotypic variation may 

 transcend genotypic in fecundity, not that it always or 

 regularly does. Because it may I wanted to point out the 

 need for great care in respect of environmental conditions 

 in interpreting results with this character. The real point 

 is this : Long experience in working with winter egg pro- 

 duction in poultry has convinced me that under properly 

 controlled environmental conditions this character is as 



